This invention relates generally to fluid driven turbines and more generally to those having a variable phase fluid driving the turbine. The variable phase may be a mixture of a gas and liquid phase; or a supercritical phase; or a supercritical phase that transitions within the device to a mixture of gas and liquid or to a pure gaseous phase; or a liquid phase that transitions within the device to a mixture of gas and liquid; or a liquid phase that transitions within the device to a mixture of gas and liquid and then subsequently transitions also within the device to a pure gaseous phase. Apparatus that efficiently converts all these fluid combinations is necessary for turbines and heat engines that optimize the production of power from heat energy, and from pressure energy in industrial processes.
Turbines are widely used in industry to convert energy in liquid streams or gas streams to shaft power. Less common, but also used are turbines to convert energy in two-phase (gas and liquid) streams to shaft power. A further requirement can be the conversion of supercritical streams and/or streams that transition from a single phase to two-phase streams. Still further applications exist for the conversion of energy in two-phase streams that transition to a gaseous stream.
At present, the turbines for each type of stream are unique to that stream. That is, a turbine configured to be gas driven is not readily usable for liquid or two-phase flow. For example, attempts to use radial inflow gas turbines for two-phase flow have resulted in poor performance and damage because the directions of centrifugal body forces are such as to throw liquid backwards into the nozzle blades.
Applicants herein believe that no efficient turbine design exists for the case of a two-phase stream which transitions to a gaseous stream within the turbine, or for a supercritical stream which transitions to a two-phase stream within the turbine or for a supercritical stream which transitions to a two-phase stream that subsequently transitions to a gaseous stream within the turbine. These instances will be referred to herein as “Transition Flows”.
Certain applications for turbines require the use of different types of fluid streams for differing conditions, as well as the use of Transition Flows. For example, a low temperature geothermal power system may require use of a gas stream or a two-phase flow stream, depending upon the temperature and working fluid used in the power producing cycle. To maximize power production, the geothermal power system may require a turbine to start in the supercritical flow regime and handle the transition to a two-phase stream within the turbine.
At present, to provide an efficient power conversion system, a new or specialized turbine must be designed, manufactured and qualified for each application. This is costly and time consuming and reduces flexibility, if the thermal characteristics of a given application change with time. There is need for an efficient turbine that can be driven by gas, or liquid or two-phase fluid flow. There is also a need for an efficient turbine that can be driven by Transition Flows.